viroids and prions
TRANSCRIPT
What are PRIONS???•Infectious agent •Composed of single sialoglycoproteins called PrP 27-30•No nucleic acidMass of 27000-30000Da•145 amino acids•Carboxyl terminus contains phosphotidylionisitol glycolipids whose components are ethanol,phosphate, myoinositol and stearic acid.
Fig(a) and (b) :Microscopic "holes" are characteristic in prion-affected tissue sections, causing the tissue to develop a "spongy" architecture
A
B
DISEASES CAUSED Cattle -Bovine spongiform
encephalopathy (BSE) or mad cow disease.
Sheep and goat- scrapie
Humans-1. Creutzfeldt–Jakob disease (CJD)2. Fatal familial insomnia (FFI)3. Kuru. etc
SIGNS AND SYMPTOMS The first symptom of CJD is rapidly
progressive dementia, leading to memory loss, and hallucinations.
Physical problems such as Stammering. jerky movements. Irritation over no issues. The disease has also been shown to result
from use of human growth hormone obtained from the pituitary glands of persons who died from Creutzfeldt–Jakob Disease.
•1730’s found in English sheep •1950-kuru•1960’s-transmittance nature•1980’s- CJD•1982- Dr. Stanley Prusnier coins the term prion.•1990s- mad cow disease•2005- new variant of CJD from beef.
History of prion
Alcohol ACID STANDARD AUTOCLAVE
METHODS. BOILING The contaminated soil is
carefully scooped up and put through a multistage incinerator that reaches up to 1200 -2000degrees F and it is further treated.
CAN PRIONS BE KILLED?
VIROIDS Viroids are plant pathogens. Viroids were discovered,
initially characterized, and named by Theodor Otto Diener, plant pathologist at the Agricultural Research Service in Maryland, in 1971.
246-469 nucleotides The first viroid to be
identified was Potato spindle tuber viroid (PSTVd). Some 33 species have been identified.
MULTIPLICATION Viriods multiply inside the nucleus of
infected plant cell by “rolling circle” mechanism, using the host enzymes.
Produce a long monomeric strand of RNA which are cut into monomers ,each monomers then join to form an individual circular viriod.
After replication , the progeny RNAs move to neighbouring healthy cells though the connecting plasmodesmata or distinct parts of the plants through phloem.
DISEASES Potato spindle tuber
disease. 1st viroid to be
identified. Natural hosts is
potatoes and tomatoes All potatoes and
tomatoes are susceptible to PSTVd and there is no form of natural resistance.
POTATO SPINDLE TUBER
DISEASE
Coconut Cadang Cadang disease
Coconut cadang-cadang viroid (CCCVd)
Every year one million coconut palms are killed by CCCVd and over 30 million coconut palms have been killed since Cadang-cadang has been discovered.
REFRENCES Google scholars.org.in National Institutes of Health. (2010). NINDS
Transmissible Spongiform Encephalopathies Information.
Cell and molecular biology by Gerald karp. Boundless. “Prions.” Boundless Microbiology. McGraw hill animations Wikipedia http://www.eppo.org/QUARANTINE/virus/
Coconut_cadang_cadang_viroid/CCCVD0_ds.pdf
Haseloff, J.; Mohamed, N.A.; Symons, R.H. (1982) Viroid RNAs of cadang-cadang disease of coconuts. Nature 299, 316-321.